Brazil to unleash GM-mosquito swarms to fight dengue

TIME to unleash the mozzies? Genetically modified mosquitoes will be raised on a commercial scale for the first time, to control dengue fever in Brazil. But it is unclear how well it will work.

Next week biotech firm Oxitec of Abingdon, UK, will open a factory in Campinas, Brazil, to raise millions of modified male mosquitoes. Once released, they will mate with wild females, whose offspring then die before adulthood. That should cut the number of dengue-carrying mosquitoes. In April, Brazil approved their commercial use.

So will they work? Margareth Capurro at the University of São Paulo studied the effects of freeing the GM mosquitoes in Jacobina in Bahia state, where a dengue alert has been in place since February due to an outbreak. Capurro's data show the number of mosquito eggs falling by an impressive 92 per cent in experimental areas. But so far this has not led to a drop in the incidence of dengue.

That may be because the study was too small, says Capurro. Only after a full epidemiological study next year will we know for sure if the GM mosquitoes are working.

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